This proposal involves two interrelated lines of investigation. The first line includes a series of protocols arranged to gain a further understanding of 1) specific correlations of changes in the synthesis of prostaglandins, in the renal content of renin and in renal hemodynamics during the development of severe and moderate renovascular hypertension; 2) humoral and hemodynamic mechanisms underlying the effects of intravascular volume expansion on severe and moderate renovascular hypertension with special reference to possible involvement of cardiopulmonary receptors; 3) humoral and hemodynamic mechanisms underlying the effects of volume contraction in severe and moderate renovascular hypertension with special reference to the effect of furosemide and to the varying concentration of circulating angiotensin. The second line of investigation is motivated by results from previous studies showing that the release of renin seems to be as dependent on beta-receptor activation as on the synthesis of prostaglandins. This second line of research involves several interrelated protocols designed with the purpose of elucidating the interaction between beta-adrenergic receptors, prostaglandin synthesis and renin release in whole kidneys in vivo and in isolated glomeruli.